Converting CoMoO4 into CoO/MoOx for Overall Water Splitting by Hydrogenation

Special structures of materials often bring in unprecedented catalytic activities, which are critical in realizing large-scale hydrogen production by electrochemical water splitting. Herein, we report a CoO/MoOx crystalline/amorphous structure as an effective bifunctional electrocatalyst for water splitting. Converted from CoMoO4 by hydrogenation, the CoO/MoOx, featured with crystalline CoO in amorphous MoOx matrix, displays superior catalytic activities toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). It shows small onset overpotentials of 40 and 230 mV for the HER and OER in 1.0 M KOH, respectively, and overall water splitting starting at 1.53 V with a robust stability. The high catalytic activity of the CoO/MoOx is benefited from the large defect-rich interface between CoO and MoOx, along with the amorphous nature of MoOx. Thus, this study demonstrates the effectiveness of structural manipulation in developing highly active electrocatalysts for overall electrochemical water splitting.